Applicant's copending application Ser. No. 557,214, filed Mar. 10, 1975 relates to the preparation of mercaptans by reacting alkyl halides with H.sub.2 S in the presence of ammonia or certain amines. The present application covers the addition of sulfur to this reaction to produce polysulfides.
It is known that alkyl polysulfides can be prepared by three general methods. One is the reaction of alkyl halides with metal polysulfides such as sodium polysulfide, the second is the reaction of mercaptans with sulfur and the third is the oxidation of mercaptans. Publications showing these various methods are as follows: for oxidation of mercaptans, G. A. Gornowicz and J. L. Speier, "Mechanisms of the Reactions of Sulfur Compounds", Vol. 3, page 55, 1968; for reaction of alkyl halides with metal polysulfides U.S. Pat. No. 3,842,111 and for the reaction of mercaptans with sulfur German OLS No. 2,405,758.
In addition, U.S. Pat. No. 3,849,471 relates to the reaction of alkyl halides with hydrogen sulfide in the presence of ethylene diamine to give alkyl mercaptans. This patent teaches, Table 3, column 9, that the reaction does not go appreciably in the presence of other amines such as tributyl amine, pyridine, and diethylene triamine (DETA). In Example 26 of the patent, the reaction of gamma-chloropropyltrimethoxysilane with hydrogen sulfide and sulfur in the presence of ethylene diamine is shown to give the corresponding disulfide. However, based upon the teachings of this patent that the reaction to form mercaptans does not go to any practical extent in the presence of other amines, it is not obvious that the process of this invention could be carried out.